Miyuki Kasahara
Tohoku University
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International Archives of Occupational and Environmental Health | 1988
Osamu Inoue; Kazunori Seiji; Takao Watanabe; Miyuki Kasahara; Haruo Nakatsuka; Songnian Yin; Gui-Lan Li; Shi-Xiong Cai; Chui Jin; Masayuki Ikeda
SummaryThe exposure intensity during a shift and the metabolite levels in the shift-end urine were examined in male workers exposed to either benzene (65 subjects; the benzene group), toluene (35 subjects; the toluene group), or a mixture of both (55 subjects; the mixture group). In addition, 35 non-exposed male workers (the control group) were similarly examined for urinary metabolites to define background levels. A linear relationship was established between the intensity of solvent exposure and the corresponding urinary metabolite levels (i.e. phenol, catechol and quinol from benzene, and hippuric acid and o-cresol from toluene) in each case when one of the three exposed groups was combined with the control group for calculation. Comparison of regression lines in combination with regression analysis disclosed that urinary levels of phenol and quinol (but not catechol) were lower in the mixture group than in the benzene group when the intensities of exposure to benzene were comparable, indicating that the biotransformation of benzene to phenolic compounds (excluding catechol) in man is suppressed by co-exposure to toluene. Conversely, metabolism of toluene to hippuric acid was suppressed by benzene co-exposure. Conversion of toluene to o-cresol was also reduced by benzene, but to a lesser extent. The significance of the present findings on the mutual suppression of metabolism between benzene and toluene is discussed in relation to solvent toxicology and biological monitoring of exposure to the solvents.
Science of The Total Environment | 1987
Takao Watanabe; Miyuki Kasahara; Haruo Nakatsuka; Masayuki Ikeda
Cigarette packs, 331 in total, were purchased in 20 areas including nine in Asia between 1982 and 1984, and analyzed for cadmium and lead by flameless atomic absorption spectrophotometry after wet digestion with nitric, sulfuric and perchloric acids. The arithmetic mean (geometric mean in parentheses) for Cd was 1.15 (1.06) micrograms/cigarette or 1.45 (1.31) micrograms/g, and the values for Pb were 1.70 (1.31) micrograms/cigarette or 1.76 (1.67) micrograms/g. The Cd content of cigarettes was distributed over a wide range from 0.29 to 3.38 micrograms/g, and the range was even wider for Pb, 0.46 to 43.66 micrograms/g. The mean values varied markedly depending on the area of production. It was not possible, however, to obtain any evidence to suggest that the differences in Cd and Pb contents are related to the area of production or the extent of industrial development of the area.
Toxicology Letters | 1986
Osamu Inoue; Kazunori Seiji; Takao Watanabe; Miyuki Kasahara; Haruo Nakatsuka; Songnian Yin; Gui-Lan Li; Shi-Xiong Cai; Chui Jin; Masayuki Ikeda
Toluene metabolism was studied in 192 Chinese workers in comparison with that in 130 Japanese and 17 Turks. Time-weighted average concentrations of toluene in the breathing zone of workers were measured utilizing passive dosimeters, and hippuric acid (HA) and omicron-cresol (omicron C) concentrations in shift-end spot urine samples by high-performance liquid chromatography (HPLC) and gas chromatography (GC), respectively. Under similar exposure conditions, male Japanese excreted almost twice as much HA as male Chinese, although such difference was less marked between female Chinese and Japanese. In contrast, the excretion of oC did not differ between the two ethnic groups. The ratio of oC over HA was highest among Turkish workers followed by Chinese, and lowest among Japanese. Possible roles of differences in toxicogenetics as well as in life patterns were discussed.
Preventive Medicine | 1986
Masayuki Ikeda; Miyuki Kasahara; Akio Koizumi; Takao Watanabe
One thousand seventy-two 24-hr diet duplicate samples were collected from inhabitants of 49 regions in various parts of Japan during the winters of 1977-1981. An additional 238 samples were collected in an adjacent summer. The samples were analyzed for sodium (Na) and potassium (K) by flame atomic absorption spectrometry and for chloride (Cl) with a chloride counter. The winter-summer differences in Na, Cl, and Na/K were essentially negligible. When the regional means of Na, K, Cl, and Na/K were compared with the 1969-1978 standardized mortality ratios of each region, positive and significant correlations were observed between winter Na and the standardized mortality ratios for cerebrovascular disease (P less than 0.01), cerebral infarction (P less than 0.01), and subarachnoid hemorrhage (P less than 0.05) in both males and females. The correlation (P less than 0.01) with the cerebrovascular disease standardized mortality ratio was further confirmed by the values for 1978-1982. In the case of the Na/K ratio, the correlation with the standardized mortality ratio for each of the three diseases was significant for men (P less than 0.01 or 0.05, depending on the disease) but not for women (P greater than 0.05). Both Na and Na/K showed significant associations with the ischemic heart disease standardized mortality ratio in men (P less than 0.05) but not in women (P greater than 0.05). In contrast, no positive association was found between Na, K, Cl, or Na/K and standardized mortality ratios for diabetes mellitus, liver cirrhosis, tuberculosis, or liver cancer (P greater than 0.05). Current blood pressure did not appear to correlate with any of the Na, K, Cl, or Na/K measurements. The validity of the present observation is discussed.
Ecology of Food and Nutrition | 1988
Haruo Nakatsuka; Miyuki Kasahara; Takao Watanabe; Shigeru Hisamichi; Hiroyuki Shimizu; Susumu Fujisaku; Yoshimi Ichinowatari; Yasuo Ida; Masanori Suda; Kunio Kato; Masayuki Ikeda
Popularity of 14 food items was investigated by questionnaires with more than thirty thousand respondents (ages ≥40 years). Half of these respondents (the urban group), lived in a prefectural city and the remaining half (the rural group), in an agricultural area in north‐eastern Japan. Four traditional items of food (rice, fish, miso soup and pickles) were frequently consumed by both groups, but they were significantly more popular in the rural group. The three non‐traditional items (bread, coffee and European tea) were taken to some extent by the urban group but they were consumed less frequently by the rural group. Thus, food habits were typically Japanese even after extensive modernization of communities in the last two decades but gradual changes are taking place. With men, bread and European tea were better accepted by the elderly than the younger‐aged in both groups; but the reverse was the case with women, indicating a sex difference in acceptance of nontraditional food items. Of particular interes...
Journal of Toxicology and Environmental Health | 1986
G.‐L. Li; S.‐N. Yin; Takao Watanabe; Haruo Nakatsuka; Miyuki Kasahara; Hiroharu Abe; Masayuki Ikeda
Female Wistar rats were exposed to various solvent vapors 8 h/d for 7 d. The leukocyte suspension and serum were prepared from peripheral blood and utilized for the determination of alkaline phosphatase (AP) activity with disodium phenyl phosphate as a substrate [leukocyte AP (LAP) and serum AP (SAP) assay]. While the exposure to benzene at 20 or 50 ppm did not cause significant changes in LAP activity, the exposure at 100 and 300 ppm resulted in a dose-dependent increase of LAP activity up to more than 100% over the control. No further increase was observed at 1000 or 3000 ppm. Similar exposure at 300 ppm to either toluene, m-xylene, n-hexane, trichloroethylene, methyl ethyl ketone, ethyl acetate, or methyl alcohol did not induce any changes in LAP activity. Thus, the increase in LAP activity was considered to be specific to benzene exposure. When the animals were exposed to toluene (300 ppm) in combination with benzene (300 ppm), not only was the benzene-induced leukopenia alleviated as previously reported, but the benzene-induced increase in LAP activity was no longer observed. The parallel inhibitory effects of toluene on benzene-induced increase in LAP and leukopenia suggest that a relation may exist between increase in LAP activity and leukopenia. No changes in SAP activities were observed in the rats under the exposure conditions examined.
Toxicology Letters | 1987
Takao Watanabe; Haruo Nakatsuka; Miyuki Kasahara; Masayuki Ikeda
Urine samples, 1163 in total, were collected in the winters of 1982 and 1983 from 132 male farmers and 1031 female farmers in 6 non-polluted areas in various parts of Japan. The urine samples were analyzed for lead concentration by means of flameless atomic absorption spectrophotometry after wet digestion followed by solvent extraction in the presence of sodium diethyldithiocarbamate. The lead concentration in urine (Pb-U; adjusted for a specific gravity of 1.016) distributed log-normally with a geometric mean (GM) of 1.81 micrograms/l (GSD = 1.99) for men (n = 132) and 2.08 micrograms/l (1.95) for women (n = 1031). No age-related changes in Pb-U were observed in either sex in the 30-79 year age range, and there was no sex-related difference in Pb-U. Analyses of female smokers together with area- and age-matched non-smokers suggested that the smoking habit would cause a significant increase in Pb-U. Comparison of the present findings with Pb-U levels published in the literature disclosed that the current Pb-levels among the Japanese population appear to be lower than the levels in Western Europe and the U.S.A.
Asia-Pacific Journal of Public Health | 1987
Kazunori Seiji; Osamu Inoue; Miyuki Kasahara; Haruo Nakatsuka; Takao Watanabe; Yt Hu; Jf Wang; Zr Wen; Sq Li; Masayuki Ikeda
Hepatitis B surface antigen and antibody (HBsAg and anti-HBs, respectively) prevalence was examined by means of solid-phase radioimmunoassay in 503 serum samples obtained from factory workers (230 men and 273 women) in Hefei, the capital city of Anhui Province, China, in 1985. The prevalence of HBsAg-positlve cases was 8% and that of anti-HBs-positive cases was 46%; the overall prevalence rate was 53% when the positivity in either of the two was considered to be indicative of hepatitis B virus (HBV) infection. There was no significant sex difference in the rate, whereas anti-HBs rate was slightly elevated in accordance with increased age. The review and evaluation of existing data in 14 articles led to a conclusion that the current HBV prevalence among Chinese populations will be in the range of 50% to 60%.
Regulatory Toxicology and Pharmacology | 1987
Masayuki Ikeda; Akio Koizumi; Miyuki Kasahara; Takao Watanabe; Haruo Nakatsuka; Yasuyoshi Sekita
In the present study, trials were performed to examine the applicability of Hayashis theory of quantification (second type) to prediction of the possible presence (i.e., detection) or absence (nondetection) of a given chemical in the environment. The dependent variables employed were the results of a nationwide environmental monitoring on pollutant chemicals conducted by the Environment Agency of Japan. When 102 chemicals were analyzed utilizing five factors as independent variables--annual production, use pattern, n-octanol/water partition coefficient (Po/w), water solubility, and biodegradability--it was found that production, use pattern, and Po/w are the major contributing factors in the prediction. Further studies with 186 chemicals utilizing these three factors as the independent variables showed that, through the combined evaluation of the results of analyses with three pairs out of the three variables, the absence of a chemical in the environment at an analytically meaningful level can be predicted with a success rate of 94.4%. The rate for the presence was 76.4%.
Industrial Health | 1987
Songnian Yin; Guilan Li; Yitang Hu; Xuemin Zhang; Chui Jin; Osamu Inoue; Kazunori Seiji; Miyuki Kasahara; Haruo Nakatsuka; Marayuki Ikeda